Photocatalytic Properties of Anisotropic β-PtX2 (X= S, Se) and Janus β-PtSSe monolayers

Abstract

The highly efficient photocatalytic water splitting to produce clean energy requires novel semiconductor materials to achieve high solar-to-hydrogen energy conversion efficiency. Herein, the photocatalytic properties of anisotropic β-PtX2 (X=S, Se) and Janus β-PtSSe monolayers are investigated based on density functional theory. Small cleavage energy for β PtS2 (0.44 J/m2) and β-PtSe2 (0.40 J/m2) endorses the possibility of their mechanical exfoliation from respective layered bulk material. The calculated results find β-PtX2 monolayers to have an appropriate bandgap (~1.8-2.6 eV) enclosing the water redox potential, light absorption coefficients (~104 cm-1), and excitons binding energy (~0.5-0.7 eV), which facilitates excellent visible-light driven photocatalytic performance. Remarkably, an inherent structural anisotropy leads to the anisotropic and high carrier mobility (up to ~5 x 103 cm2V−1S−1) leading to fast transport of photogenerated carriers. Notably, the small required external potential to derive hydrogen evolution reaction and oxygen evolution reaction processes with an excellent solar to-hydrogen energy conversion efficiency of β-PtSe2 (~16%) and β-PtSSe (~18%) makes them promising candidates for solar water splitting applications.